adding `withoutIn` for deep property removal

[y-nk]

I had this need to remove a property from a dictionary within my state.

with a state structure like :

{
   pool_of_items: {
     ...ids : Object
   },
   visible_items: {
      ...ids : occurence_number
   }
}

I can now call state.withoutIn(['visible_items'], item_id) to remove a key from my dictionary and keep it with a clean structure of item.id => number_of_occurence_on_screen.

I tried my best to keep the coding fashion you used. Let me know if you need any adjustment or if you feel there is an other way of doing this.

[rtfeldman]

This has been pending changes for about two months, so I'm going to close it as stale.

Please feel free to reopen with those changes! :)

[AfrazHussain]

Any chances of re-opening and merging this? I can contribute to another similar PR if necessary.

[y-nk]

I honestly forgot about this (since i was using my own fork at the time). I'll try again and put test coverage this time.